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When assigning a task, even if there does not seem to be enough free time between two tasks that are already assigned, it may be possible to insert a task by updating the changeover setup time. While accurate assignment result can be obtained with such insertion assignment, when a few operations search for assignment position for continuous resources, as the result, it might waste time failing to look for available insertion position. This property specifies whether or not to strictly search for such an insertion assignment position. If you do not wish such an insertion assignment, you can set it to "No" in order to finish the reschedule in a shorter time.
For example, suppose that operation A, operation B, and operation C are assigned to resource R1, and operation B and operation C have setup times as shown in Figure 1. Operation X is assigned to this resource with finite capacity and based on a forward assignment direction. Assume that the earliest start date and time of operation X is earlier than operation A in the past. The amount of resources in the calendar and the amount of resources required for each task are all set to 1. There are four possible locations to do insertion assignment, indicated by red arrows.
Figure 1 (Horizontal axis is time)
Ja
Strictly check will be preformed to see if insertion assignment is possible by calculating the changeover setup times for positions 1, 2, 3, and 4 in the mentioned order. As soon as a possible position is found, it will be set as the temporary assignment position.
It will look for possible position based on simple judgements done by ignoring setup time and purely based on if there is enough empty time to assign production time, Let's assume it is position 1. However, suppose that a changeover setup occurs between operation X and operation A, and operation X cannot be assigned to position 1 (Figure 2).
Figure 2.
The next step is to strictly check if the assignment is possible at position 2. Operation Xs changeover setup time with operation A and operation B is 0 second, short enough for insertion assignment to take place. (Figure 3 shows an example where the changeover setup time is 0 seconds. )
Figure 3.
A position where insertion assignment is possible has been found, and this position will be the temporary assignment result. Position 3 and 4 will not be checked if insertion is possible.
Nein
As in the case of "Yes", we will strictly check if it is possible to perform insertion assignment at position 1. However, once position 1 is checked to be not possible for insertion. By selecting "No", it will not move on to check position 2. Instead, it will find a new position that is possible for production time to be assigned, while future changeover setup time had been assigned. In this example, we will skip position 2 and find position 3. In position 3, we will strictly check if insertion assignment is possible. As a result, operation X has short changeover setup time with operation B and C. If assignment is done as shown in figure 4, position 3 will be the result for a temporary assignment.
Figure 4
If position 3 is unavailable due to the changeover assignment with between operation X and operation B and C, it will check for possible insertion position in the future beyond position 4. A new possible position for insertion will be strictly checked once an empty spot for assigning production time is available while future changeover setup time had been assigned. This process will continue until a position that can be assigned to an insertion assignment is found.
If the assignment direction is backward, the same process will be performed, but in reverse.
In short, when this property is set to "yes," as long as the distance between the operations is wide enough to allow the production time of the operation to be temporarily assigned, it will re-calculate the changeover setup times strictly in order to confirm whether or not insertion assignment is possible. This process take a certain amount of time. If insertion assignment kept being impossible, overall rescheduling time will be very long. If it is clear in advance that an insertion assignment like the one in Figure 3 will not occur in the first place, you can get the same result in a shorter rescheduling time by setting this property to "No".
When the resource split conditional expression is set
When the split condition expression for resources is set, no matter how close operations and production time are, there might be possibility for production time of temporary assigned operations to be inserted. Thus, it tends to have a longer time for assignment.
Figure 5 shows the case where the production time of operation X is longer than the time between the production times of operation A and operation B. If the resource split conditional expression is not set, the changeover setup time for operation A and B do not even have to be calculated to understand that it is impossible to perform an insertion assignment in position 2. Even if the property is set to "yes", strict check for position 2 will be skipped.
Figure 5.
However, if a resource split conditional expression is set, there is possibility of split assignment occurs as shown in Fig. 6, so a strict assignment check will be performed at position 2.
Figure 6.
However, if a resource split conditional expression is set in a way that insertion assignment cannot be performed, like shown in figure 6, unnecessary check will be performed, resulting in a longer rescheduling time. If you know in advance that insertion assignment will not occur, you can set it to "No".
Summary: When to set this property to "No"
These are the following two cases. 1. When the changeover setup time is set, but shortening the changeover task still cannot make insertion assignment possible. 2. When a split condition expression for resources is set, but no insertion assignment can occur by the split or division.
Actual customer results (Machine spec: Windows 10 Pro 20H2, Intel(R) Core(TM) i7-7820X CPU @ 3.60 GHz 3.60 GHz, 128GB memory)
| Kunde | Vorgangsanzahl | Planungsdauer | Beschleunigung | |
|---|---|---|---|---|
| Ja | Nein | |||
| A | 9.000 | 00:44:57 | 00:00:07 | ~450x |
| B | 1.500.000 | 06:47:00 | 05:05:00 | ~1,3x |
Beispiele
Sample data is available to check this function. As sample data is beyond the limitations of the trial version, so it cannot be run in the trial version.
Beispiel X-1
This will give you the same result whether the strict search property is set to "yes" or "no", but you can reschedule in about 15 seconds with "yes" and less than 1 second with "no" (1).
In this data, the item setup table is set. In the third and fourth lines, Item X is set with a 0 second changeover task with item A and B, but the sort order is smaller than the first and second lines, it will not work.
The third and fourth lines will be effective if the "sort order" is greater than 10. For example, if you set the value to 100 as shown in the above figure, and set "do detailed search when inserting operation" to "yes", the insertion assignment will occur as shown in the following figure. It takes about 10 seconds to reschedule.
When the order of the third and fourth rows of the item setup table is set to 100, and do detailed search when inserting operation" is set to "yes".
If we continue to reschedule with "do detailed search when inserting operation" set to "no", the reschedule will take less than a second, but the insertion point will no longer be strictly searched, resulting as the following If you need to obtain an insertion assignment like the one shown above, this property should be set to "yes" or left empty. If it is clear in advance that no insertion assignment will occur, you can shorten the rescheduling time by setting to "no".
Beispiel X-2
Sample X-2 is an example of a case where a split condition expression is set for a resource. A conditional expression is set up to split the operation when an interruption of more than 1 second occurs. In the figure below, the operation of Item X is divided into two parts, of a production quantity 0.5 and 0.5. This will give you the same result whether the strict search property is set to "yes" or "no", but you can reschedule in about 8 seconds with "yes" and less than 1 second with "no".
1 Machine Specs: OS Windows 8.1 (64bit), Inter(R) Core(TM) i7-5960X CPU @ 3.00GHz 3.00GHz
Hinweise
- If this property is empty, it is defaulted to be "yes".
- The changeover setup time also includes the setup time and teardown time that are deleted by the plan setting of "zero setup for the same item". Click here for more information on changeover setup times.
- Setting this property with a default value in the property definition settings will slightly slow down the reschedule speed. It is recommended to set the value without setting the default value.
- This property is added in Ver.16.3.1.7.
